Borgarvirki Fortress, View L1004494

Borgarvirki - the Citadel is a columnar basalt fortress and a volcanic plug on Vatnsnes peninsula in northwest Iceland. It is 10-15 m high and 177 meters above sea-level. It might have been used as an old Viking fortress, at least some legends claim that it was, but we don't know this for sure.

Source: guidetoiceland.is/connect-with-locals/regina/borgvirki-fortress-in-north-west-iceland